For the list_participants() method, we can add the 'NOT IN" operator. The addNotInCondition() methos already exists in the CDbCriteria class;

In app/helpers/remotecontrol/remotecontrol_handle.php

Line 2332
$allowedOperators = ['<', '>', '>=', '<=', '=', '<>', 'LIKE', 'IN', 'NOT IN'];

Then add the condition

elseif ($operator === 'NOT IN') {
/* @var mixed /
$values = array_slice($valueOrTuple, 1);
$oCriteria->addNotInCondition($columnName, $values);
}

I have attached the updated file